nothing really, just history repeating itself!
go watch some of the charts and you can see the cycles very clearly. there is always times that almost all the altcoins go up in pump after pump and rise their ATHs but eventually all of this will end as the investors take their money out and invest in back into bitcoin or take their bitcoin out buy dumping their altcoins.
some of them don't get dumped overnight but they all will get dumped for sure.